FIG. 1 illustrates a contactless payment card 100, which is for example a VISA, MASTERCARD or other type of credit or debit payment card. The contactless payment card 100 comprises an RFID (radio frequency identification) transponder 102, which allows contactless communication with a terminal 104. In particular, terminal 104 comprises a reader 106, which is able to communicate with the RFID transponder 102. The contactless payment card 100 may also comprise a contact interface 108, allowing payments to be made using a card reader (not shown) that makes physical contact with the card 100, as an alternative to the contactless interface.
An advantage of contactless payment cards is that payment may be made without removing the card from its wallet, and wear and tear is reduced when compared to cards that make physical contact, such as those using a magnetic strip or chip contacts to communicate with a terminal.
Payment card 100 may be used to pay for a wide range of products or services, in shops, hotels, transport networks etc. However, certain services, such as mass transit systems, may receive a high number of users, and there is a technical problem in processing payment transactions by contactless payment cards sufficiently quickly to avoid congestion at the entrance to such services.